1. Field of the Invention
This invention relates to a method of making an aqueous based magnetic particle dispersion and more particularly to a method of making photographic elements having a transparent magnetic recording layer using an aqueous based dispersion of magnetic particles with gelatin as the major hydrophilic binder.
2. Description of the Related Art
U.S. Pat. No. 5,147,768 contains an example of ferromagnetic particles dispersed in water and then mixed with gelatin to form a final dispersion used to coat a cellulose triacetate film to prepare a transparent magnetic recording layer. A problem exists in such preparations in that it is extremely difficult to prepare uniform dispersions which do not interfere with the photographic properties of photographic elements to which the transparent magnetic recording layer is applied.
It has been found by experimentation that improvements in the quality of the transparent layer can be gained by incorporating into the aqueous ferromagnetic particle dispersion suitable dispersing agents. However, even with the presence of suitable dispersing agents in the aqueous ferromagnetic particle mixture, flocculation of the magnetic particles occur when mixed with gelatin, thereby causing grain in the finished photographic element.
Thus, there is a need to provide aqueous ferromagnetic particle dispersions containing gelatin suitable for making high quality transparent magnetic recording layers that are readily compatible with other gelatin based photographic elements.